Unauthorized incursions of aircraft and ground vehicles onto runways and taxiways can often have catastrophic results. The number of aircraft accidents that occur on the ground is nearly three times the number of aircraft accidents that occur in the air.
In degraded visual conditions the problem becomes even greater since the ground controller is often reliant on non-visual information such as voice communication from the cockpit crew reporting the aircraft's current position on the airport surface, or display information from a ground surveillance radar system. Unfortunately, only twelve airports in the United States have ground surveillance radar systems to aid the controller. The remainder of the U.S. airports depend on the visual observations of the controller and position reports from pilots. The problem gets even worse. The twelve surface radar systems that do exist are often over twenty-five years old, difficult to maintain, and provide ironically inadequate information in poor weather when radar is needed most. As a result, the controller in the tower is almost completely reliant on his visual observations and surface position reports from aircraft crew to provide situational awareness of the current state of the airport surface. In degraded visual conditions, the controller is often asking the question "where are you?" to aircraft crews to provide his situational awareness of the airport surface. As a result, the controller has to maintain a mental image of the airport surface, rather than having hard surveillance data available.
The current state of surface traffic control and several solutions to this problem are discussed in an article entitled "Airport Surface Traffic Automation" in The Lincoln Laboratory Journal, Volume 4, Number 2, 1991 by Ervin F. Lyon. The article discusses several alternatives such as the Airport Surface Traffic Automation (ASTA) plan of the Federal Aviation Administration, and the Airport Movement Area Safety System (AMASS) currently under development by Norden Systems, a subsidiary of the assignee of the present invention. AMASS operates in conjunction with and receives radar data from an ASDE-3 ground surveillance radar which utilizes high resolution radar electronic surveillance to provide tower controllers with all weather surface surveillance capability. AMASS processes the ASDE-3 data to detect and track airport ground traffic, predict where the aircraft/vehicles will be a fixed time later (e.g., 10 seconds), and alert controllers of possible runway incursions and ground collisions with sufficient time to allow corrective action to be taken.
The ASTA system envisions incorporating the functions of the ASDE-3 and AMASS, along with a system of automatic runway status lights to improve the situational awareness of the pilots and vehicle operators. Other variations of the ASTA system include even greater sophistication and fusion of data to provide an elaborate system to provide better airport surface situational awareness information. Each of the alternatives proposed in The Lincoln Laboratory Journal paper is a technically feasible system that is sorely needed. However, these systems may be prohibitively costly and complex to make widespread availability possible.
A lower cost, near term system is required to solve the problems of airport surface control, thus enhancing airport safety and reducing delays.